Here is some more info on the pump, that Mizuno just sent me: IWAKI magnet pump, MD-6K-N Max capacity: 8/9 ℓ/min Max head: 1.0/1.4
100V 12W/60Hz, 12W/50Hz He plugged it into the WattChecker which shows it is drawing 10.8 W. (I thought it was 5 W just by feel. Not a bad guess!) Based on the efficiency of the other MD 6 model (18 W in 3 W out), that would deliver ~1.8 W to the water, but I expect this is less efficient. My guess is still 0.25 to 0.50 W because I think this system would detect 1.8 W and nothing shows up when the pump alone is running. However much heat it adds, the losses exceed it. That is what the data shows. He is going to repeat the test where he runs it for several hours or a day with just the pump. The last time he did that, there was less insulation so it was not as sensitive, but I believe 1 W would have showed up.
